If your baby has been crying a lot and has runny poo that’s causing a red bottom, you might be concerned about lactose intolerance. And if your child is showing symptoms like these, proper diagnosis and treatment is important.

What is lactose intolerance?

Lactose intolerance happens when the body can’t break down a sugar called lactose.

Lactose is present in all breastmilk, dairy milk and other dairy products. It makes up around 7% of breastmilk and infant formula.

Usually, the enzyme lactase, which is produced in the small intestine, changes the lactose into glucose and galactose – sugars that are more easily absorbed. But sometimes children don’t produce enough lactase to break down all the lactose, so the unabsorbed lactose passes through the gut without being digested. Bacteria eat the undigested lactose, which leads to a build-up of gas and causes symptoms like wind and diarrhoea.

Lactose is important for a baby’s health and development. It provides around 40% of a baby’s energy needs and helps him absorb calcium and iron.

Causes of lactose intolerance

There are two types of lactose intolerance: primary and secondary. They have different causes.

Primary lactose intolerance

This happens when babies are born with no lactase enzymes at all. This is genetically carried and extremely rare. Babies with this kind of lactose intolerance have severe diarrhoea from the first day of life. To thrive, they need a special diet from the time they’re born.

Secondary lactose intolerance

This can happen if a child’s digestive system is upset by tummy bugs like gastroenteritis, which cause temporary irritation of the lining of the stomach and small intestine. This kind of lactose intolerance is temporary and usually improves after a few weeks.

Conditions like coeliac disease can also cause secondary lactose intolerance. Once these conditions are being managed properly, lactose intolerance shouldn’t be a problem.

Secondary lactose intolerance might also happen if your child’s body doesn’t produce enough lactase. This usually develops after the age of three and can be lifelong. Some people are more likely to develop it than others. For example, people from a Northern European background are generally less likely to develop it. People from Asia and Africa are more likely to get it.

Most lactose-intolerant children can continue to include some milk products in their diets, especially if they eat them with other foods and in small amounts throughout the day. These foods are an important source of nutrients, especially calcium.

Common symptoms of lactose intolerance

Without lactase, the lactose in milk doesn’t get absorbed and stays in the gut. As bacteria in the gut eat the lactose they produce large amounts of gas. This causes a range of symptoms including:

  • wind

  • pain and swelling in the tummy

  • crankiness

  • failure to settle

  • coming on and off the breast during breastfeeding

  • failure to gain weight

  • diarrhoea

Red, raw diaper rash caused by acidic poo is another possible symptom or side effect of lactose intolerance. You should put a good protective cream on your baby’s bottom if this happens.

Even if your child has these symptoms, it doesn’t always mean she’s lactose intolerant. Some or all of these symptoms are common in healthy breastfed infants. The symptoms can happen in the first week of life and last up to six weeks or as long as five months. It’s also highly likely the symptoms will disappear.

As long as your baby’s weight and health aren’t suffering, it’s not likely there’s a problem. But it’s always wise to consult your General Practitioner (GP), especially if your child has diarrhoea that isn’t getting better and he’s under three months old.

Sometimes lactose intolerance is confused with food allergies like cow’s milk allergy. Some common food allergy symptoms include vomiting, blood or mucus in diarrhoea, hives and swelling around the eyes – these aren’t symptoms of lactose intolerance. If your child has symptoms like these, you should see your GP for proper diagnosis.

Diagnosing lactose intolerance

Because some of the symptoms of lactose intolerance and food allergy are similar, diagnosing lactose intolerance can sometimes be tricky.

Methods used to diagnose lactose intolerance include the following:

  • Hydrogen breath test: This tests the amount of hydrogen gas in the child’s breath. Lactose-intolerant children have higher levels of hydrogen in their breath.

  • Elimination diet: This involves removing foods containing lactose from the child’s diet to see whether symptoms improve. If the symptoms come back once the foods are reintroduced, lactose intolerance is most likely the cause of the problem.

Even if your baby is diagnosed with lactose intolerance, she’ll continue to thrive once you sort out the problem. Talking to a health professional about your baby’s nutritional needs is important. You could start with your GP or paediatrician.

What to do about your child’s lactose intolerance

The treatment for lactose intolerance often depends on the cause. And no matter what’s causing your baby’s lactose intolerance, it’s important to soothe and comfort your baby when he’s showing symptoms.

Primary lactose intolerance

If your child has primary lactose intolerance, your GP, paediatrician or dietitian will guide your child’s treatment.

Secondary lactose intolerance

For a breastfed baby with secondary lactose intolerance caused by gastroenteritis, you should be able to continue breastfeeding.

Weaning isn’t usually recommended because breastmilk has so many nutritional benefits and lactose is good for your baby’s growth. Your child can usually tolerate a small amount of lactose, and gradually increasing it can help her body produce more lactase.

If your baby is formula fed or you’re considering giving him formula, consult your GP or a registered dietitian before using or changing to a low-lactose or lactose-free infant formula. If your child is under six months, avoid using soy-based infant formula.

Talk to your GP if you’re thinking of using Lacteeze drops in expressed breastmilk or Lacteeze tablets. There’s some debate about the effectiveness of these treatments. Also talk to your GP if you want to try replacing breastmilk or alternating breastmilk with formula.

Lactose intolerance and diet

If your child is older and diagnosed with lactose intolerance, the following food and diet tips can help. These tips also apply to adults with lactose intolerance.

These foods are OK:

  • Cheeses with very small lactose content – brie, camembert, cheddar, colby, cotto, edam, fetta, gouda, havarti, mozzarella, parmesan, Swiss and Tilstat

  • Yoghurt – the bacteria in yoghurt breaks down the lactose so it’s usually fine for your child to eat

  • Calcium-fortified soy products – soy yoghurt, milk, ice-cream and cheese

  • Lactose-free milk

  • Butter and cream – these contain only small amounts of lactose and are usually fine to eat

  • Bread, cereals, fruit, vegetables, meat and other protein foods

Watch out for these foods:

  • Milk ice-cream, milk desserts, cream cheese, processed cheese and cheese spread

  • Muesli bars

  • Instant mashed potato and vegetables with added milk or white sauces

Check the ingredients in these foods:

  • Biscuits, cakes and cake mixes

  • Soups

  • Mayonnaise

  • Milk chocolate

These diet tips can also help your child avoid symptoms:

  • Try full-fat milk – the fat gives your child’s body longer to digest the lactose.

  • When cooking, try roasts, grilled vegetables and Asian-style stir-fries.

  • For dessert, try lemon sorbet, frozen fruit desserts, meringue, fruit baskets and milk-free muffins.

Lactose overload

Lactose overload isn’t the same as lactose intolerance – that is, it isn’t a problem with the production of lactase. Rather, lactose overload happens when a baby consumes large amounts of lactose at one time and can’t break it all down.

Lactose overload can happen when:

  • mothers have a natural oversupply of breastmilk in their baby’s early weeks

  • breastfed babies feed frequently and alternate breasts before the breasts have been emptied

  • breastfed babies have a pattern of short breastfeeds – sometimes mothers shorten breastfeeds because of problems like sore nipples or mastitis or to comfort babies with colic

  • breastfed babies drink more first milk than last milk. The lactose-rich first milk passes through the digestive system faster than the last milk, and there’s not enough time for all the lactose to be broken down

  • bottle-fed babies drink a lot of milk (this isn’t common).

If your child has symptoms of lactose overload, feed her in a position that ensures she gets all the milk from each breast. For example, feed from one breast only for a four-hour block before moving onto the other breast for the next four hours. If over-feeding is causing the overload, try not to feed more often than every three hours.

© raisingchildren.net.au, translated and adapted with permission

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